Demolding apparatus

ABSTRACT

A gripper (2) for removing a molded workpiece (9) from the opened mold (1, 3) of a molding machine is coupled through a step-up drive transmission with the ejector (13, 15, 17) associated with the mold in such a manner that the ejector causes it to execute a movement away from the ejector in the same direction of motion as the ejector. The drive transmission can in particular have co-operating limit stops (45, 43) on the ejector and on the gripper, and one of these limit stops is mounted on a drive step-up lever (37). In another embodiment, the step-up drive transmission is designed as a hydraulic transmission.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a demolding apparatus for a molding machine.Such demolding apparatuses are used in particular in the case ofinjection-molding machines for the production of plastic moldings, butcan also be used in molding machines of other types, such as for examplediecasting machines, molding presses and the like.

With such a demolding apparatus, the demolding operation proceeds asfollows: firstly, the mold is opened by moving the mold halves apart.Then the gripper is made to run into the opened mold. Subsequently, theejector carries out its ejecting stroke, so that the molding ispartially moved out of the mold cavity by means of one or more ejectorpins and brought into the gripping region of the gripping member, sothat it can be grasped by the gripping member. Then the moving awaymovement is carried out by the gripper or the gripping member--inrelation to the gripper--parallel to the direction of ejection, in orderto release then completely from the mold cavity the molding held by thegripping member and also lift it off the ejector pins. This moving awaymovement of the gripper can also begin already before the ejector hasreached the end point of its ejecting stroke. After carrying out themoving away movement, the running out movement of the grippertransversely to the direction of ejection can then be performed, bywhich the molding held by the gripping member is moved out of the moldinto a position where the molding can be removed for further treatmentor further transport. The various movement operations of the mold, ofthe gripper and of the ejector must be carefully coordinated with oneanother and carried out partly with time overlap, in order on the onehand to avoid time loss and achieve a high cycle rate of the machine,but on the other hand to eliminate with certainty the risk of mutualhindrance of these movements and of damage to the moving parts, even inthe case of drive malfunctions.

In the case of the hitherto customary demolding apparatuses of thistype, a separate drive is required for carrying out the moving awaymovement of the gripper or of the gripping member parallel to thedirection of ejection, said drive being provided in addition to thedrives for opening and closing the mold, for actuating the ejector andfor the running in and out of the gripper. This drive for the movingaway movement constitutes an additional constructional expenditure,which makes the overall apparatus more expensive and also moresusceptible to malfunctions. The components of this drive to be fittedon the gripper or gripping member increase the mass to be moved eachtime the gripper is run in and out. The main problem is, however, tocontrol the drive for the moving away movement in optimum timecoordination with the movements of the ejector drive and the otherdrives in such a way that least possible time losses occur and highestpossible cycle rates of the molding machine are possible.

In the case of drives to be activated separately, unavoidable timelosses occur owing to the response times and switching times of theassociated switches, signal generators and the like and to the requiredacceleration times.

The object of the invention is to design an apparatus of the said typein such a way that it is simplified in terms of construction and controland permits an optimum and loss-free coordination of the moving awaymovement of the gripping member with the ejecting movement of theejector.

The way in which the object is achieved according to the invention is byproviding a demolding apparatus for removing a molding from a moldingmachine. The demolding apparatus comprises a gripper for entering themolding machine when the molding machine is in a open position, anejector for injecting the molding in a direction of injection, anejector drive acting on the ejector for carrying out an ejecting stroke,and means for moving the gripper, or the gripping member which formspart of the gripper, together with the molding, in a direction parallelto the direction of ejection and away from the ejector. The ejectordrive is coupled, at least during the final part of the ejecting stroke,to one of the gripper and the gripping member by means of a drivetransmission. The drive transmission has a step-up ratio greater thanone.

The invention dispenses with the need for a separate drive for themoving away movement of the gripping member, and this moving awaymovement is controlled by direct drive transmission from the ejectordrive. A considerable constructional simplification is attained as aresult. Time losses due to response times and switching times cannotoccur.

Embodiments of the invention are explained with reference to thedrawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified block diagram, partly in section, of ademolding apparatus according to a first embodiment;

FIG. 2 shows a second embodiment in a similar representation;

FIGS. 3 and 4 show two further embodiments in a still further simplifiedrepresentation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, the two mold halves of a mold of an injection-molding machineor other molding machine are represented by 1 and 3 and are movable inrelation to each other in the direction of the arrow 5 in order to closeor open a mold cavity 7. With the mold open, a molding 9, for example aninjection molding, molded in the mold cavity 7, can be ejected by meansof the ejector 11 from the mold cavity 7. The ejector 11 comprisesejector pins 13, which are borne by an ejector plate 15, which can bemoved back and forth in the direction of the arrow 19 by means of anejector drive 17, for example a hydraulic cylinder.

Between the opened mold halves 1, 3, a gripper 21 can be made to run inand out in the direction of the arrow 23. The gripper 21, which may bepart of a separate handling device, robot or the like, comprises agripper arm 25, on which a gripping member 27 is movably mounted. Thegripping member 27 comprises a gripper plate 29, which bears suckers 31which face the molding 9 and are connected to a vacuum source (notshown). The gripper plate 29 is mounted displaceably o the gripper arm25 by means of guide pins 33. Instead of the suckers 31, other grippingelements known per se, for example for mechanical gripping of themolding 9, may also be provided.

The movement of the gripping member 27 can be controlled by means of alever arm 37, which is mounted on the gripper arm 25 in a swivel bearing39 and is connected at its end to the gripper plate 29 via a joint 41.At a point lying between the bearing 39 and joint 41, the lever arm 37bears a stop 43, on which a push rod 45, connected to the ejector plate15, can act.

The apparatus operates as follows: after opening of the mold halves 1,3, or already during the opening movement, the gripper arm 25 is made torun in the direction of the arrow 23 between the mold halves 1, 3. Whenthe gripper arm 25 has reached its end position, or already during thelast part of the running-in movement, the ejector drive 17 begins toactuate the ejector plate 15 in the direction of arrow 19 for theejecting stroke, so that the ejector pins 13 engaging the molding 9release the latter from the bottom of the mold cavity 7 and move it inthe direction of the suckers 31 of the gripping member 27, until themolding 9 bears against the suckers 31 and is held by them. This takesplace at a point in time at which the molding 9 has not yet completelylost contact with the mold half 3.

On continued movement of the ejector plate 15 in the direction ofejection 19, the push rod 45 comes to bear against the stop 43, so thatthen the lever arm 37 is moved and turned into the position 37,indicated by dot-dashed lines. As a result, the gripping member 27 ismoved together with the gripped molding 9 in the direction of the arrow19 further away from the mold half 3 and closer to the gripper arm 25.On account of the different lever arm lengths between the stop 43 andthe lever bearing 39 or between the joint 41 and the lever bearing 39,in this process the movement of the gripping member 27 is performed atgreater speed than the movement of the ejector plate 15. Push rod 45,stop 43 and lever arm 37 consequently represent a stepping-up(transmission ratio greater than 1) drive transmission between theejector drive 17 and the gripping member 27. Consequently, during thelast part of the ejecting stroke of the ejector drive 7, the grippingmember 27 carries out a moving away movement parallel to the directionof ejection 19. Since this is performed at greater speed than theejecting movement of the ejector pins 13, the molding 9 gripped by thegripping member 29, 31 is not only moved completely out of the moldcavity 7, but also lifted off the ejector pins 13, so that, on thesubsequent running out movement of the gripper arm 25, it can then bemoved along oppositely to the direction of arrow 23, without beinghindered in the process by the mold half 3 or the ejector pins 13. Inthe run-out position of the gripper arm 25, the gripping member 29, 31can then be returned into the advanced position, before or after removalof the molding 9. For this purpose, the running-out position of thegripper arm 25 may be assigned returning elements (not shown), which aredesigned either as fixed stops or guides or as active elements and acton the gripper plate 29 in the sense of returning movement.

The push rod 45 is, of course, arranged offset with respect to the moldcavity 7, perpendicularly to the plane of the drawing of FIG. 1, in sucha way that it does not hinder the running out of the gripper 25 with themolding 9. The push rod 45 also need not be taken laterally past themold half 3, as shown, but may be taken through the mold half 3 by meansof a guide. In order to change the point in time of impact of the pushrod 45 against the counter-stop 43 or the extent of the moving awaymovement of the gripping member 29, 31, the push rod 45 and/or thecounter-stop 43 may be designed to be adjustable. As an example of suchan adjustable arrangement, it is shown in FIG. 1 that the push rod 45 isguided adjustably in a holding means 48 and can be fixed in its positionby a nut 46.

Departing from the embodiment according to FIG. 1, the entire gripperarm 25 may be mounted movably parallel to the direction of ejection andexecute the moving up movement. A separate movable mounting means of thegripper member on the gripper arm is then not required. Furthermore, thedrive-stepping-up lever linkage need not be provided on the gripper, butmay also be located on the mold side between the ejector drive 19 andthe push rod 45. The drive transmission also need not be designed as amechanical linkage, but may also be designed, for example, in the formof a hydraulic coupling. Such different embodiments are represented inFIGS. 2 to 4, which are described below. In this description, partswhich have already been described with reference to FIG. 1 and areprovided with the same reference symbols are not explained again.

In the case of the embodiment according to FIG. 2, the gripper arm 25 isdisplaceable by means of a guide carriage 51 in a guide 53 parallel tothe direction of arrow 5. In the running-in and running-out direction 23of the gripper arm 25, the guide 53 can be moved together with thegripper arm 25 by means of a drive (not shown). On a lever 37, which ismounted on the guide and on the gripper arm such that it can swivel at38 and 40, there is located a counter-stop 43, against which a push rod45, moved by the ejector plate 15, comes to bear during the ejectingmovement of the ejector. As a result, a moving away movement of theentire gripper arm 25 parallel to the direction of ejection is effected,the lever arm 37 providing for a stepping up of the drive. In the caseof this embodiment, a gripping member mounted movably on the gripper arm25 is not required, rather the end section 25a of the gripper arm 25forms the gripping member, to which the suckers 31 or other grippingelements are directly attached.

In the case of the embodiment according to FIG. 3, just as in FIG. 2 theentire gripper arm 25 is mounted movably parallel to the direction ofejection 5 (not shown in FIG. 3). Mounted rigidly on the ejector arm 25is the counter-stop 43, against which the push rod 45 acts. However,unlike in the case of the embodiments according to FIGS. 1 and 2, thepush rod 45 is not rigidly connected to the ejector plate 15, which canbe actuated by the ejector drive 17. Instead, a lever 55 is provided,the one end of which is mounted at 57 on the mold 3, and which isconnected jointedly in its central region at 59 to the ejector plate 15.At the other end, the lever 55 is connected jointedly at 61 to the pushrod 45. When the ejector drive 17 moves the ejector plate 15 in thedirection of ejection, this movement is transmitted via the lever 55with stepping-up to the push rod 45, so that the latter moves forwardmore quickly than the ejector plate 15 and the molding 9 and during thecourse of the ejecting stroke meets the counter-stop 43, so that thenthe gripper arm 25 executes the moving away movement to the left in FIG.3 together with the molding gripped by the suckers 31.

Also in the case of the embodiment according to FIG. 4, the entiregripper arm 25 is mounted displaceably (not shown) parallel to thedirection of arrow 5 and bears a fixedly arranged counter-stop 43. Onthe latter there acts a push rod 45, which is mounted on the mold 3 andcan be driven hydraulically by means of a piston 63 and hydrauliccylinder 65. The ejector drive 17 is--as also in the case of theembodiments according to FIGS. 1 to 3 --designed as a hydrauliccylinder, and a line 67 connects the rod-side working space of thehydraulic cylinder 67 to the piston-side working space of the hydrauliccylinder 65. The effective cross section of the hydraulic cylinder 65 isless than that of the hydraulic cylinder 17. If pressure medium isadmitted to the piston-side working space of the drive cylinder 17, inorder to carry out the ejecting stroke of the ejector plate 15 and ofthe ejector pins 13, the pressure medium displaced out of the rod-sideworking space of the cylinder 17 is forced into the piston-side workingspace of the cylinder 65, so that the piston 63 is displaced to the leftin FIG. 4 with push rod 45, so that it strikes the counter-stop 43 and,by means of the latter, drives the gripper arm 25 to the left for themoving away movement. The different cross-sectional surface areas of thedrive cylinders 17 and 65 produce a stepping-up of movement, so that theadvancing movement of the piston 63 and of the push rod 45 is performedat greater speed than the advancing movement of the ejector plate 15 andof the ejector pins 13.

Further modifications and refinements are possible within the scope ofthe principle of the invention. For example, the hydraulic drivetransmission according to FIG. 4 may also be used if not the entiregripper arm 29 but a gripping member mounted movably on the gripper armcarries out the moving away movement, as in the case of the embodimentaccording to FIG. 1. Also, for example in the case of the embodimentaccording to FIG. 1, the coupling of the counter-stop 43 with thegripper plate 29 could be performed not mechanically by means of a lever37 but, for example, hydraulically. Also, the gripper may be equippedwith a drive by which an approaching movement up to the molding 9 orstop 45 is executed.

In an advantageous refinement of the invention, in the case of theembodiments according to FIGS. 1 to 3, the push rod 45 and/or thecounter-stop 43 can be combined with spring elements and/or shockabsorbers, so that an abrupt striking of the push rod 45 against thecounter-stop 43 is prevented or cushioned and deadened.

In a further refinement of the invention, it may be provided that thestepping-up ratio of the transmission is variable. For example, in thecase of using a stepping-up lever according to FIGS. 1 to 3, one of thebearing points 39, 40, 41 of the lever 37 may be designed adjustably insuch a way that the stepping-up ratio is changed by altering theeffective lever arm length. In the case of the hydraulic transmissionaccording to FIG. 4, there may be connected to the connecting line 67 abranch with an adjustable restricting point 68, by which an adjustablepart of the hydraulic fluid flowing through the line 67 can be drainedoff, so that the quantity of hydraulic fluid flowing to the cylinder 65is adjustable.

The invention has been represented with reference to the exemplaryembodiments only in conjunction with one ejector and one gripper. It is,of course, also applicable if the same mold is assigned a plurality ofgrippers, for example for removing a plurality of moldings from amulti-cavity mold. Furthermore, the invention is applicable in the caseof multi-level molds, in which a plurality of molds, in each caseprovided with ejector systems, are arranged one after the other in themanner of levels and a plurality of grippers can be made to run inbetween the opened molds. In the case of all such systems operating witha plurality of grippers, in application of the invention each gripper oreach gripping member can be driven by the respectively assigned ejectorsystem by a corresponding stepping-up drive transmission for the movingout movement.

I claim:
 1. A demolding apparatus for removing a molding from a moldingmachine which is adjustable between a closed position and at least oneopen position, the demolding apparatus comprising a gripper for enteringthe molding machine when th molding machine is in an open position,including a gripping member, an ejector for ejecting the molding in adirection of ejection, an ejector drive acting on the ejector forcarrying out an ejecting stroke, the ejecting stroke having at least aninitial part and a fall part, and molding withdrawal means for moving atleast one of the gripping member and the gripper together with themolding in a direction parallel to the direction of ejection forcarrying out a moving away movement of the molding from the ejector, themolding withdrawal means including a drive transmission coupling theejector drive, at least during the final part of the ejecting stroke, toone of the gripper and the gripping member, the drive transmissionhaving a stepping-up ratio greater than 1 for enhancing the moving awaymovement of the molding from the ejector.
 2. The apparatus as claimed inclaim 1, wherein the gripping member is movably mounted on the gripperin a direction parallel to the direction of ejection and the drivetransmission includes means for carrying out the moving away movement.3. The apparatus as claimed in claim 1, wherein ejection occurs at afirst ejecting speed, and the molding withdrawal means includes a stopwhich is movable by the drive transmission in a direction parallel tothe direction of ejection and which, during the ejecting stroke of theejector, comes to bear against and moves along a counter-stop connectedto one of the gripper and the gripping member, the ejector drive beingconnected to the stop by the drive transmission, which drives the stopat greater speed than the first ejecting speed of the ejector.
 4. Theapparatus as claimed in claim 1, wherein ejection occurs at a firstejecting speed, and the molding withdrawal means includes a stop and acounter-stop, the stop being movable by the ejector drive in thedirection of ejection and which during the ejecting stroke of theejector comes to hear against and moves along a counter-stop, thecounter-stop being connected to one of the gripper and gripping memberby the drive transmission, which drives the one of the gripper and thegripping member at greater speed than the speed of the stop.
 5. Theapparatus as claimed in claim 4, wherein the drive transmissioncomprises a pivotally mounted lever, by which the counter-stop isconnected at a first distance from the pivot axis and the gripper or thegripping member is connected at a second, greater distance from thepivot axis.
 6. The apparatus as claimed in claim 3, wherein the drivetransmission comprises a pivotally mounted lever, which the ejectordrive engages at a first distance from the pivot axis and which isconnected at a second, greater distance from its pivot axis to the stop.7. The apparatus as claimed in claim 3, wherein the ejector drive has afirst hydraulic cylinder, and the apparatus has a second hydrauliccylinder for moving the stop in a direction parallel to the direction ofejection, wherein the effective cross-sectional surface area of thesecond hydraulic cylinder is less than that of the first hydrauliccylinder and wherein the apparatus includes a connection line fordisplacement of a pressure medium from the first hydraulic cylinder tothe second hydraulic cylinder.
 8. The apparatus as claimed in claim 1,wherein the stepping-up ratio of the drive transmission is adjustable.9. The apparatus as claimed in claim 4 wherein at least one of the stopand the counter-stop is adjustable in relation to the other of the stopand the counter-stop.
 10. The apparatus as claimed in claim 3, whereinat least one of the stop and the counter stop includes at least one of aspring element and a shock-absorbing element.
 11. A apparatus forremoving a molding from a molding machine which is adjustable between aclosed position and at least one open position, comprising:a gripper forentering the molding machine when the molding machine is in an openposition, the gripper including a gripping member for gripping themolding, ejector means for ejecting the molding in a first direction,ejector drive means for driving the ejector means in an ejecting strokehaving an initial part and a final part, an molding withdrawal means formoving the gripper or gripping member together with the molding awayfrom the ejector means in a direction parallel to the first direction,the molding withdrawal means including drive transmission means forcoupling the ejector means to the gripper during at least the final partof the ejecting stroke, the drive transmission means having astepping-up ratio greater than 1 for enhancing the movement of themolding away from the ejector.
 12. The apparatus as claimed in claim 11,wherein the gripping member is movably mounted on the gripper in adirection parallel to the first direction and is movable relative to thegripper by the drive transmission in order to move the gripping memberaway from the ejector in a direction parallel to the first direction.13. The apparatus as claimed in claim 11, wherein ejector occurs at afirst ejecting speed, and the molding withdrawal means comprises a stopwhich is movable in a direction parallel to the first direction by thedrive transmission, and, during ejection, the stop bears against andmove along a counter-stop which is connected to one of the gripper andgripping member, the ejector drive means being connected to the stop bythe drive transmission means in order to drive the stop at a greaterspeed than the first ejecting speed of the ejector means.
 14. Theapparatus as claimed in claim 11, wherein the molding withdrawal meanscomprises a stop which is moved by the ejector drive, and which, duringejection, bears against and moves along a counter-stop, which isconnected to one of the gripper and gripping member by the drivetransmission means in order to drive the one of the gripper and grippingmember at a greater speed than the speed of the stop means.
 15. Theapparatus as claimed in claim 14, wherein the drive transmission meanscomprises a pivotally mounted lever, by which the counter-stop means isconnected at a first distance from the pivot axis and the gripper or thegripping member is connected at a second, greater distance from thepivot axis.
 16. The apparatus as claimed in claim 13, wherein the drivetransmission means includes a pivotally mounted lever which the ejectordrive means engages at a first distance from the pivot axis and which isconnected at a second, greater distance from its pivot axis to the stop.17. The apparatus as claimed in claim 13, wherein the ejector drivemeans has a first hydraulic cylinder, and the apparatus has a secondhydraulic cylinder for moving the stop in a direction parallel to thefirst direction, the effective cross-sectional surface area of thesecond hydraulic cylinder being less than that of the first hydrauliccylinder, and wherein the apparatus includes a connection line fordisplacing a pressure medium from the first hydraulic cylinder to thesecond hydraulic cylinder.
 18. The apparatus as claimed in claim 11,wherein the stepping-up ratio of the drive transmission is adjustable.19. The apparatus as claimed in claim 13, wherein at least one of thestop means and the counter-stop means are adjustable in relation to theother of the stop means and the counter-stop means.
 20. The apparatus asclaimed in claim 13, wherein at least one of the stop means andcounter-stop means includes at least one of a spring element and ashock-absorbing element.